Carburetor



Sept. 11, 1928. 1,684,085

. J. J. YCRAIN CARBURETOR Filed May 15, 1923 A TTORNEY Patented Sept. 1 11, 1928.

JOHN .T. GRAIN, 0F WATERBURY,-GONNECTICUT.

CARBURETOR.

Application filed May 15,

This invention relates to carburetors for internal combustion engines, and more particularly to a carburetor in which liquid fuel is first vaporized by heat and then mixed with air.

One object ofthe invention is to provide a carburetor in which liquid fuel is vaporized in a conical chamber by the heat from the exhaust gases of an internal combustion engine,

A further object is to provide a carburetor of the above nature in whichthe. porportion of fuel vapor to air in the explosive mixture will be automatically maintained constant irrespective of the load of the en- A further object is to provide a carburetor of the above nature which will be adapted to operate efiiciently upon any liquid fuel capable of being completely volatilized by the application of heat.

A further object is to provide a carburetor of theabove nature which will be relatively simple, cheap to manufacture, and very eflicient and durable in use.

With these and other objects in view, there has been illustrated on the accompanying drawings one form in which the inven- V tion may be conveniently embodied in practice.

The single figure'shown on the drawing represents a longitudinal sectional view taken through the carburetor.

One of the chief disadvantages of the spray type of carburetors now in general use is the difliculty of securing complete vaporization of the fuel, and this difliculty is greater the higher the boiling point of the fuel used. Consequently, suchcarburetors cannot generally be employed on kerosene or other high-boiling point fuels, but are limited to the lighter and more volatile fuels, such as gasoline. By means of the present invention, the above and other disa advantages have been avoided, and a carburetor has been produced which will operate not onl upon gasoline, but upon kerosene and ot 181 less volatile heavy oils. The use of the present form of carburetor thus greatly enlarges the range of fuels which can be employed to operate internal-combustion engines. 'Referring now to the drawing in which like reference numerals denote correspond- 1923. Serial No. 639,097.

ing parts, the numeral 10 denotes a fuel vaporizing chamber, preferably conical in shape, and having a series of horizontal ex-' ternal fins llsurrounded by a jacket 12. The jacket 12 is provided with an inlet pipe 13which is connected with the exhaust manifold of an internal combustion engine. The jacket 12 also has an out-let pipe let for discharging the gases to the atmosphere or to amuffler, not shown. In order to increase the interior surface of the vaporizer 10, a series of vertical fins 15 are provided, extending inwardly from the cpnical sides of the vaporizer.

The flow of fuel into the vaporizing chamber 10 is controlled by a float feed device generally denoted by 16. The float feed device 16 comprises a receptacle 17 having a float 18 slidable vertically therein. Upon the to of the float 18 is a guide rod 19 fitted within a vertical recess 20 in a cover 21, screwed upon the top of said float chamber 17. The bottom of the float is rovided with'another rod 22 located withm a depending tube 23, said rod 22 being provided with a conical member 24 seating upon the bottom end of the tube 23. V

The float chamber 17 is connected to the vaporizing chamber 10 by means of a pipe 25 which has one end screwed into the tube 23,'its other end screwed into a T member 27, the latter being connected to the bottom of said conical vaporizing chamber 10 by a short vertical pipe 28. The T member 27 is also connected by a pipe 25 to a valve 28 adapted to be opened and closed by a handle 29. The valve 28 is connected by means of a short elbow pipe 30 to an electric starting vaporizer 31 for use before the carburetor has been warmed up by the engine exhaust gases.

- The lower end of the tube 23. is closedby a cup member 32, said cup member 32 being float chamber 17 and in the vaporizing chamber 10, the float chamber 17 is provided near its-top with a pipe 34 leadlng to a passage 35 in the valve housing 36. said passage 35 opening downwardly intothe vaporizing chamber. The valve housing 36 is provided with a base section 36 adapted to rest upon a flange 36 on the top of the vaporizing chamber '10. The flange 36 is Y secured to the base section 36 in any suitablemanner, as .bymeans of screws 36.

The valve housing 36 is provided with a vertical passage 37 in which is located a rotary valve 38, pivoted at 39. The vertical passage 37 opens intoa horizontal cylinder 40 at 'a point slightly above the valve 38 within which cylinder is located an automatically operated control member 41 The control member 41 has a pair of cylindrical end pistons 41 and 41 and an intermediate conical portion 7 42. As will be clear, the flow of fuel vapor up through the vertical passage 37 will be impeded to a greater or less extent according to the position of the intermediate conical portion 42 relative to the vertical passage 37.

. The piston-41 is connected by means ofa piston rod 43 to a piston 44 of considerably larger diameter, said piston 44 being adapted to fit within a hollow cylinder 45. The upper portion of the passage 37 above the control member 41 is connected by passages 46 and 47 to the small and large hollow cylinders and respectively.

provided for connecting the left-hand end of the large hollow cylinder 45 with the inflowing air in a; mixing chamber 49. The vaporv ized fuel from the vertical passage 37 of the 'valve housing- 36 is adapted to pass up through a- Vertical pipe 50 from which the vapor is transferred to the mixing chamber 49 through a pair of horizontal pipes 51 and The mixing chamber. 49 is provided with a lower cylindrical air inlet sec'tio 53, and an 'upper cylindrical fuel dischargmg section 54, between which sections" is a Venturi constriction 55. The narrowest portion or throat of the Venturi constriction 55 is provided in its circumference with a series of small perforations 56 through which the fuel vapor is received'from an annular box 57 co nnected to the pipe 51. The flow of the combustion mixture is controlled b a throttle 57 located in the upper cylindrlcal.

section 54. The section 54 is provided with a flange 57 by means of which the carburetor may be connected'tothe intake manifold of the engine. The lower horizontal pipe 51 carries the greater part of the fuel vapor into the mixing chamber, while the upper pipe, 52, which is considerably smaller in diameter than the pipe 51, serves merely as aby-pass for a small amount of rich fuel vapor when the engine is running idle wlth the throttle closed. In order to Vary-the amount of fuel passing through the pipes 51 and 52, a pair of adjustable valves and 59 are provided for said pipes respectively. The lower valve 58 comprises a horizontal conical member 60 adapted to seat in the left-- hand end of the pipe 51 and adapted to be adjusted bymeans of a screw 61 threaded into an enlarged boss 62 in alinement with the pipe 51. The upper valve 59 is located in alinement with the by-pass pipe 52 and has a conical section 63 adapted to be adjusted by means of a screw 64 threaded into a boss 65, in alinement with the pipe 52.

The air-inlet section 53 of the mixture chamber 49 is provided at its bottom with a pair of lips partially encircling the exhaust pipe 13 but spaced slightly therefrom, whereby the air drawn through said space will be heated by contact with said pipe 1.3. The air inlet section 53 is provided with a series of perforations 66 surrounded by a rotatable sleeve 67, said sleeve also having perforations adapted to aline with the perfora'tions 66. By adjusting the position of said sleeve 67., the amount of cold air drawn in through the perforations 66, for mixing with the heated air from below, may be readily varied.

In order to'supply the engine with a rich mixture for starting from cold condition. the starting vaporizer. 31 is connected through a pipe 68 to the fuel discharging section 54 of the mixing chamber at a point above the throttle 57*, and in approximate alinement with the by-passpipe 54. The fuel in the auxiliary starting Vaporizer 31 'is heated by a spiral electric heating coil 69 connected at its ends to conductive wires 70 and 71, said wires being supplied with current preferably from a suitable storage battery, not shown. In the operation of the carburetor disclosed, the hotexhaust gases from gine will herein. 7 I the enpass continuously through the pipe 13 and the jacket 12, thereby heating the fins 11 on the conical chamber 10. The heat from the outside of the chamber will be rapidly conducted through the walls there- .of, and will maintain the interior fins 15 at i a high temperature. By means of this construction, the effective heating'surface of the fins 15 and the inside of theconical chamber 10 will increase with in said conical chamber, which depth in turn is dependent upon the load of the engine. The heating surface is proportional to the square of the depth, since the surface area of the sides of a cone increases as the square of the altitude. If the engine demandis great, the vapor pressure in the top of the conlcal vaporizing chamber 10 will diminish,

the depth of the fuel,

and the level of the fuel will then be per: mitted to rise somewhat, thereby increasing the amount of effective heating surface in contact with the liquid. The rate of vaporization of fuel will thus be increased.

If on the other hand the engine demand is small, the vapor pressure above the liquid in the conical chamber will increase and force the liquid back through the pipes 25 and 33 into the fuel supply tank. The level will thus be lowered and this will diminish the rate of vaporization.

, lated by adjusting the valve 58.

Under normal running conditions, when the carburetor has been thoroughly warmed up, theliquid and vapor in the vaporizing chamber 10 will reach a condition of equilibrium, the composition of the vapor distilling from the surface being then identical with that of the liquid supplied to the vaporizing chamber. The float 18 and the depending rod 22 are so proportioned that under normal pressure, the level of; liquid fuel in the vaporizing chamber 10 will lie slightly below the top of the fins 15.

After being volatilized, the fuel vapor travels through the passage 37, through the ipes and 51, and enters the mixing chamber 49 at the Venturi throat where it mixes with the incoming air from below. The relative proportion of fuel to air may be regu- This proportion will then vbe automatically maintained by the action of the control member (not shown).

41 which will reciprocate in the cylinders 40 and 43 and vary the position of the cone member 42 in accordance with the engine demand.

If the vapor pressure in the passage 37 is greater than the pressure of the air in the air-inlet portion 53, the force applied to the right of the piston 44 will overbalance that applied on the left. The control member 41 will then be moved to the left, thereby throttling down the passage 37 and increasing the back pressure, which will instantly depress the level of the liquid in the vaporiz- 10, by forcing it out through the valve 24 and up into the supply tank The amount of efifective heating surface will thus be reduced and this will in turn lower the rate of vaporization. If, on the other hand, the vapor pressure in the passage 51 is smaller than the pressure of the air in the. air-inlet portion 53, the control member 41 willnbe moved to the right so as to allow more vapor to travel through the ing chamber passage 37. The back pressure will thereby reduced and the level of liquid in the vaporizing chamber 10 will rise, causing the rate of vaporization to again increase.

By means of this construction, it will be seen that the rate of vaporization. will be automatically varied in such a manner that the pressure of thefuel vapor in the passage 37 and that of the air in the air-inlet portion will be continuously equalized. In other words, the pressure drop of the fuel vapor in passing through the valve 58 will be the same as the pressure drop of the air in passing from the air-inlet portion 53 to the Venturi throat of the mixing chamber. Consequently, since the fiow of gas is dependent upon the relative pressure drop, the ratio of fuel to air will be maintained practically constant for any volume of flow. The value of this ratio may be permanently set by the adjustment of the valve 58.' The more this valve is opened, the richer the mixture, and conversely closing it gives a leaner mixture.

When the engine is idling, or running at a low speed, the mixing chamber '49 will be supplied with fuel vapor through the pipe 52 beyond the throttle 64, the amount of such supply being determined by the adjustment of the valve 59.

In order to regulate the temperature of the incoming air-'which should be high enough to prevent condensation of the fuel vapor in the mixing chamber'the adjusting sleeve 67 should be rotated to admit the proper quantity of cold air through the perforations 66. When the engine is started from cold condition, the valve 29 will be opened, permitting the liquid fuel to flow into the electric vaporizing chamber 31. The electric current should then be turned on to heat the coil 69 which will yaporize the fuel surrounding it. The vapor will then be drawn up through the pipe 68 in the fuel discharging section. Suflicient vapor will be generated by the electric vaporizer 31 to run tire engine light until the heat of the exhaust has started the main vaporizer, at which time the current may be turned off and the valve 28 may be closed.

, When the engine is to be permanently stopped, the valve 38 will be closed, wl1ereupon the vapor pressure will force the liquid fuel back out of the carburetor into the supplv tank through the pipe 33.

While there has been disclosed in this specification one formin which the invention may be embodied, it is to be understood that this form is shown for the purpose of illustration only, and that the invention is not to be limited to the specific disclosure, but may- 1. In a carburetor for an internal-combustion engine, a heated chamber for vaporizing a poolof liquid fuel, means for mixing the fuel vapor with a supply of air, and an automatic pressure-operated mechanism for maintaining a constant ratio of fuel to air,

the invention,

: engine. I

2. In a carburetor for an internal-combus and means controlled by the vapor pressure in the engine intake for varying the level of said liquid fuel in the chamber in accordance with the demand for fuel from the tion engine, a heated fuel-vaporizing chain'- ber-adapted to contain a pool of liquid fuel,

, means for mixing the fuel vapor with a sup ply of air, an automatic pressure-operated "valve to maintain a constant ratio of fuel to air irrespective of the load on the engine, and-an adjustable mixture valve to determine the value of said ratio, and means responsive to the pressure in the engine intake for varying the level of said liquid fuel in the chamber in accordance with the demand for fuel from the engine.

3. In a carburetor for an internal-combustion engine, a heated fuel-vaporizingchamber, a mixing chamber, means for mixi'ng the fuel vapor with a supply of air in sald mixing chamber and .an automatic. pressure-operated. valve to maintam a constant ratio of fuel to air irrespectlve of the load on the engine,,an adjustable mixture valve to determine'the value of said ratio,

means for delivering an auxiliary supply of vapor to said mixing chamber for use while the engine is idling, an adjustable auxiliary mixture valve for said means,

and a check-valve-operated float feed for limiting the maximumheight of the fuel level in said vaporizin chamber.

4. In a carburetor or an internal-combustion engine, a,- heated fuel-vaporizing chamber, a second'chamber for mixing the fuel vapor with a supply of air, a throttle,

"an automatic pressure-operated valve to maintain a constant ratio of fuel to air irrespective of the demand of the engine, an

adjustable mixture valve to determine the value of said ratio, means for delivering an auxiliary supply of fuel vapor to the mixing chamber at a point above the throttle, a check valve-operated float feed inf] mechanism for limiting the maximum height of the fuel level in said vaporizing chamber,

and an auxiliary electric heater for vaporizing a portion of the supply of fuel to permit the engine to start from cold condition. V i

5. In a carburetor for an internal-combustion engine, a heated fuel-vaporizing chamber, a second chamber for mixing the fuel vapor with a supply of air, an'automatic pressure-operated valve to maintain a constant ratio of fuel to air irrespective of the demand of the engine, an adjustable mixture valve to determine the value of said ratio, an auxiliary passage for delivering fuel vapor to said mixing chamber to enrich the mixture while the engine is idling, an adjustable valve for'said auxiliary passage, :1. check valve-operated float feed mechanism th bore, a valve for limiting the maximum height of the fuel level in said vaporizing chamber, and a heater for warming the air supply.

6. In a carburetor for an internal combustion engine, a conical vaporizing chamber adapted to. contain a liquid fuel, means for heating the outside of said vaporizing chamber from the exhaust of said engine, means for mixin air with said fuel vapgr,

and means controlled by the flow of the vapor-air mixture for varying the surface of liquid fuel in contact with the heated walls of said chamber in accordance with the load of the engine. 7. In a carburetor'fer 'an internal-com bustion' engine, a conical fuel vaporizing chamber having a series of horizontal fins on its exterior and adapted to contain a Q pool of liquid fuel, a casing surrounding said chamber for causing the hot exhaust gases from the engine to heat said chamber, the top of said chamber being closed by a valve housing, a horizontal slidable cone valve for controlling the flow of fuel vapor,

the sliding movements of said cone valve being responsive to theidemand of. the engine, and means controlled by .the flow of the fuel vapor-air mixture for varying the level *of the liquid fuel in said chamber in accordance-with the load of the-engine.

8. In a carburetor for an internal-combustion engine a heated fuel-vaporizing chamber, means for mixing the fuel vapor with a supply of air, a conical valve for throttling the supply of vapor, said valve having a pair of balanced pistons connected thereto, a third piston connected to the balanced pistons, means for subjecting opposite sides of said third piston to the pressures of the supply of air and vapor of the fuel vapor-air mixture in the engine intake for varying the level of the liquid fuel in said chamber in accordance with the load of the engine.

10. In a device of the character described, a vaporizing chamber adapted to contain a liquid fuel, means for heating said chamher, a valvecasing connected to said cham her and having a .vapor' passageway extending through the same, said, casing having a differential bore, a pair of pistons slidably mounted in the smaller portion of' connected to said pistons and controlling said passageway, a third piston connected to said pair of pistons a conduit connecting said pipe to the other -end of the larger portion of said bore, am

a conduit placing said passageway in com- 10 munication with said pipe.

In testmony whereof, I have aflixed my signature to this specification.

JOHN J. GRAIN. 

